dear Jessicat, hello and welcome to the forum with a very sad post.
My first hopes are that your first baby will be delivered without any complications and that both you and the baby are both well as you are at the time to give birth.
I do know what I want to say here, but I have to be very careful because we don't want to lose you from the site, simply because you have come here to ask for help and reassurance.
How absolutely disappointed you must be to know that your partner has left you 'high and dry', and I'm so sorry for saying this, because a brand new mum always needs their partner/spouse there for support, as do other mums with a couple of children.
I have a real fear here for the first weeks of feeding your baby, that you aren't overcome by depression, however this may have happened already I don't know, but suspect it maybe the case.
I know that's it's not appropriate for me to forecast this and I hope that I am wrong.
Love is so important in a marriage or by having a relationship, especially when you both have a child together, but in this situation it seems to be going only one way.
I also have a big worry that the father can be physically abusive and that he has no respect for you, by cheating on you, and it's uncertain how many times this has happened, so he will need to have a big overhaul to stop all of this, and that could be so hard to do, maybe he doesn't care, which then brings me to if you got back together, what will he do to you in 4, 5 or so years down the track, and it's this that I am so fearful for you.
If a person cheats on you and tells you that they don't love you, it's probably not going to change, as they want their freedom back.
I am sorry and I know that this reply may hurt and upset you, but it's coming from an old head, but please I hope that you can reply. L Geoff. x